This invention relates to an image input device and in particular to a real time digital radiographic device for diagnosing a patient, while digitizing X-ray images in real time, taking-in them and proceeding to an image processing.
As a prior art real time digital radiographic (hereinbelow abbreviated to DR) device there is known, for example, a device described in JP-A-61-113432. The device described in the publication stated above was provided with scanning modes for two numbers of scanning lines, 525 and 1125. These two modes were switched over selectively, depending on the use, and images consisting of a number of pixels 512.times.512 or 1024.times.1024 were taken-in. On the other hand U.S. Pat. specification No. 4,204,225 describes the efficiency to increase the number of scanning lines for a television camera from 256 to 1024 and to proceed to a processing for taking-in a high resolving power image as well as various sorts of possible devices. Further, in JP-A-60-111635, it is described that a 4000 line scanning is also possible, taking it into account to use an image pickup tube of about 5 inch.
In addition, a co-pending application, U.S. Ser. No. 220,978, filed July 18, 1988 now U.S. Pat. No. 4,881,124, by a part of the applicants of this application describes the switching over of the scanning lines of 525 and 1050 and the change of the horizontal and the vertical scanning frequencies corresponding thereto.
However, according to these prior art techniques, the compatibility in the pixel unit, i.e. the fact that imaging is effected always with a same central position and a same image area for these plurality of operational modes, was not taken into account.
Furthermore, when a real time DR device of next generation provided with scanning modes of numbers of scanning lines greater than 1500 or 2000 is developed, restrictions are produced in the utilization of the techniques on hardwares, softwares, etc. developed for the existing devices and smooth exchange between different devices is difficult.